Background Clinical assessment of intravascular volume status is challenging. In humans, ultrasonographic assessment of the inferior vena cava diameter, directly or as a ratio to the aortic diameter is used to estimate intravascular volume status. Objectives To ultrasonographically obtain reference values (RV) for caudal vena cava diameter (CVCD ), area (CVCa ) and aortic ratios using 3 views in awake healthy dogs. Animals One hundred and twenty-six healthy adult dogs from clients, students, faculty, or staff. Methods Prospective, multicenter, observational study. Two observer pairs evaluated CVCD by a longitudinal subxiphoid view (SV), a transverse 11th-13th right hepatic intercostal view (HV), and a longitudinal right paralumbar view (PV). Inter-rater agreements were estimated using concordance correlation coefficients (CCC). For body weight (BW)-dependent variables, RVs were calculated using allometric scaling for variables with a CCC ≥ 0.7. Results The CCC was ≤0.43 for the CVC/aorta ratio at the PV and ≤0.43 in both inspiration and expiration for CVC at the SV. The RVs using allometric scaling for CVCa at the HV for inspiration, expiration, and for CVCD at the PV were 6.16 × BW0.762 , 7.24 × BW0.787 , 2.79 × BW0.390 , respectively. Conclusions and clinical importance The CVCD , measured at the HV and PV in healthy awake dogs of various breeds has good inter-rater agreement suggesting these sites are reliable in measuring CVCD . Established RVs for CVCD for these sites need further comparison to results obtained in hypovolemic and hypervolemic dogs to determine their usefulness to evaluate volume status in dogs.

Establishment of reference values of the caudal vena cava by fast-ultrasonography through different views in healthy dogs

BACKGROUND: Rectal fluid administration may offer a simple, safe and inexpensive alternative to intravenous or nasogastric fluid therapy in equine clinical cases. OBJECTIVES: To evaluate the tolerance and effects of rectally administered fluid and compare the measurements of haemodilution and intravascular volume with those during nasogastric and intravenous fluid administration. STUDY DESIGN: Randomised controlled experimental trial. METHODS: Six clinically normal Standardbred geldings were used in a 4‐way crossover study: each received three different fluid treatments (intravenous, nasogastric and rectal) at 5 mL/kg/h for 6 h and underwent a control (no treatment) with water and feed withheld. Bodyweight was measured at baseline and 6 h. Packed cell volume (PCV), total solids (TS), albumin, electrolytes, lactate, urine specific gravity, vital parameters, gastrointestinal borborygmi and central venous pressure were measured every 2 h. RESULTS: Rectal fluid administration with plain water was well tolerated and caused clinical chemistry changes consistent with haemodilution, indicating absorption. Mean (95% confidence interval) PCV decreased from 40% [40–42] at 0 h to 35% [34–36] at 6 h during rectal fluid treatment (P<0.001), similar to decreases in PCV occurring also with i.v. and nasogastric (NGT) treatment (P<0.001). The TS also decreased with i.v. and rectal fluid (P<0.001). There was a decrease in bodyweight in the control (P<0.001) but not with any of the fluid treatments. MAIN LIMITATIONS: A small sample size of healthy, euhydrated horses and a relatively short duration of fluid administration was used. CONCLUSIONS: Rectal fluid administration requires clinical evaluation, but may offer an inexpensive, safe alternative or adjunct to i.v. fluid administration, particularly when administration via NGT is not possible or contraindicated. The Summary is available in Portuguese ‐ see Supporting Information

Continuous fluid infusion per rectum compared with intravenous and nasogastric fluid administration in horses

POCUS: AFAST – Clinical Integration

The objective of this study was to calculate the collapsibility index (CI) in a group of 15 healthy adult mixed breed cats via right hepatic intercostal ultrasound view. The minimal and the maximal diameters of the caudal vena cava (CVC) were obtained during inspiration and expiration, respectively, then CI was calculated. The mean diameter of the CVC was 0.5cm. The mean CI was 28±3% and CI was not significantly associated with gender. As in human medicine, there is a growing need for less invasive monitoring in small animal practice. The CI enables the assessment of estimated volemia without the need for a central venous catheter. This is the first reported study investigating CI in cats.

/pdf/caudal-vena-cava-collapsibility-index-in-healthy-cats-by-gyit175co8.pdf

Caudal vena cava collapsibility index in healthy cats by ultrasonography

Background Ultrasonographic measurement of the vena cava and aorta (Ao) diameters and their ratios have been suggested to be a reliable way of quantifying hypovolemia. Objective To evaluate the feasibility and reliability of an ultrasonographic technique for measurement of Ao and caudal vena cava (CVC) and derived ratios using three different acoustic windows in a population of healthy neonatal foals. Correlation between Ao and CVC measurements and ratios and foals' age or bodyweight were also investigated. Methods In 14 healthy foals aged less than 7 days, the diameters of the Ao and of the CVC in long and short axis were measured by two observers from images obtained using three different ultrasonographic imaging planes (left dorsal, left ventral and right views). The Ao and CVC cross-sectional area and the CVC/Ao diameter and area ratios were calculated. Image quality was subjectively assessed. Intraobserver and interobserver reliabilities for image quality scores and measurements were evaluated between the two observers. Simple linear regression models were used to identify correlations between the CVC/Ao measurements and ratios and the age and bodyweight of the foals. Results The left ventral view showed the highest reliability. A correlation between bodyweight and the short axis measurement of the CVC was found (R2 = 0.385; p = 0.018). Age was positively correlated with the long axis of measurement of the CVC (R2 = 0.426; p = 0.011) and CVC/Ao diameter ratio (R2 = 0.625; p = 0.001). Conclusions The left ventral view allows the Ao and CVC cross sections to be easily visualized and measured in neonatal foals in right lateral recumbency.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/vms3.506

Transabdominal ultrasonographic measurement of caudal vena cava to aorta derived ratios in clinically healthy neonatal foals.

Background
Intravascular volume assessment in foals is challenging. In humans, intravascular volume status is estimated by the caudal vena cava (CVC) collapsibility index (CVC-CI) defined as (CVC diameter at maximum expiration [CVCmax] – CVC diameter at minimal inspiration [CVCmin])/CVCmax × 100%.

Hypothesis/Objectives
To determine whether the CVC could be sonographically measured in healthy foals, determine differences in CVCmax and CVCmin, and calculate inter- and intrarater variability between 2 examiners. We hypothesized that the CVC could be measured sonographically at the subxiphoid view and that there would be a difference between CVCmax and CVCmin values.

Animals
Sixty privately owned foals <1-month-old.

Methods
Prospective study. A longitudinal subxiphoid sonographic window in standing foals was used. The CVCmax and CVCmin were analyzed by a linear mixed effect model. Inter-rater agreement and intrarater variability were expressed by Bland-Altman and intraclass correlation coefficients, respectively.

Results
Measurements were attained from 58 of 60 foals with mean age of 15 ± 7.9 days and mean weight of 75.7 ± 17.7 kg. The CVCmax was significantly different from CVCmin (D = 0.515, SE = 0.031, P < 0.001). Inter-rater agreement of the CVC-CI differed by an average of −0.9% (95% limits of agreement, −12.5 to +10.7%). Intrarater variability of CVCmax was 0.540 and 0.545, of CVCmin was 0.550 and 0.594, and of CVC-CI was 0.894 and 0.853 for observers 1 and 2, respectively.

Conclusions and Clinical Importance
These results indicate it is possible to reliably measure the CVC sonographically in healthy foals, and the CVC-CI may prove useful in assessing the intravascular volume status in hypovolemic foals.

M.C. Tuplin

Papers

Influence of the Respiratory Cycle on Caudal Vena Cava Diameter Measured by Sonography in Healthy Foals: A Pilot Study.